Conventionally, as a disc device of this type, a device disclosed in Japanese Unexamined Patent Publication No. 2011-204311 A is known, for example. The disc device disclosed in Japanese Unexamined Patent Publication No. 2011-204311 A includes a magazine including a plurality of magazine trays each storing one disc, and a plurality of disc drives. The disc device disclosed in Japanese Unexamined Patent Publication No. 2011-204311 A is structured such that: an arbitrary magazine tray is drawn out from the magazine; one disc stored in the drawn out magazine tray is suctioned and held by a suction pad; and the disc is placed on the tray of an arbitrary disc drive. Further, the disc device disclosed in Japanese Unexamined Patent Publication No. 2011-204311 A is structured such that discs supplied to a plurality of disc drives, respectively, are suctioned and held by the suction pad one by one, to be returned to an arbitrary magazine tray.
In recent years, with the progress of cloud computing, it is required to further increase data capacity in the disc device. In order to increase the data capacity, simply thinking, the number of magazines should be increased and the number of discs to be stored should be increased.
However, an increase in the number of pieces of magazines inevitably increases the distance between the disc drive and a magazine that is placed at the farthest position from the disc drive. This invites an increase in the disc conveying time. Further, since the disc device disclosed in Japanese Unexamined Patent Publication No. 2011-204311 A is structured to convey the disc one by one between the magazines and the disc drives, considerable time is required for replacing the discs supplied to a plurality of disc drives by next discs.
Accordingly, the applicant has developed a disc device including a carrier which retains a plurality of discs in a stacked state, which supplies the retained plurality of discs to a plurality of disc drives, respectively, and which collects the supplied plurality of discs in a stacked state.
With the disc device, since a plurality of discs can be collectively conveyed between the magazine and any disc drive, the time required for replacing the discs supplied to a plurality of disc drives by next discs (hereinafter referred to as the disc replacing time) can be drastically suppressed.
However, this disc device still remains a matter of improvement in suppressing the disc replacing time.
(Expertise which Forms Basis of Present Disclosure)
With the aforementioned disc device developed by the applicant, discs are replaced in accordance with the procedure shown in FIG. 61.
Firstly, a first plurality of discs supplied to a plurality of disc drives, respectively, are collected by the carrier in a stacked state (Step S11).
Next, the first magazine tray is conveyed to the pass position (Step S12). Here, “the pass position” refers to the position where a plurality of discs can be passed from the carrier to any magazine tray or from any magazine tray to the carrier.
Next, the carrier stores the collected first plurality of discs in the first magazine tray (Step S13).
Next, the first magazine tray is returned to a prescribed position (Step S14).
Next, the second magazine tray is conveyed to the pass position (Step S15).
Next, the carrier retains the second plurality of discs stored in the second magazine tray (Step S16).
Next, the second plurality of discs retained by the carrier are supplied to a plurality of disc drives, respectively (Step S17).
Thus, replacement of the discs is completed.
The inventors have made the following findings as a result of an extensive study on a further reduction in the disc replacing time. The inventors have found that the disc replacing time can be drastically suppressed by: in place of allowing the carrier to immediately store the collected first plurality of discs in the first magazine tray, allowing the carrier to retain, in addition to the collected first plurality of discs, the second plurality of discs stored in the second magazine tray; and allowing the second plurality of discs to be supplied to a plurality of disc drives. Based on the expertise, the inventors arrived at the following disclosure.